Technically Speaking: Exhaust System

Q: I’m interested in replacing my C5’s stock exhaust system, and I’m hoping you can help me determine which one is right for me. I’m looking for an aggressive sound and improved performance.

I also have a question on header selection. Specifically, should I purchase the long- or short-tube variety?

I don’t have a repair shop in my area that I trust to do the insulation, but I’m a good shade-tree mechanic. Do you think I could perform this installation in my home garage? If so, could you give me some tips to make the job easier?

Johnny

Via email

A: The C5’s factory exhaust system sounds decent and is extremely efficient. However, due in part to government decibel restrictions, the muffler design is not as free flowing as we’d like. As a result, there’s horsepower to be gained by installing a less restrictive system.

The first thing to keep in mind when purchasing an exhaust system is the quality of construction. If you go with a company that has a proven product, you usually will not be disappointed.

My suggestion is to go to several Corvette events and see which system sounds the best to you. Then, ask the car’s owner the following questions:

- Who manufactured it?
- Did he install the system himself, or have it done by a professional?
- Have there been any problems since the installation, such as rattles or a check-engine light?
- Did the kit come complete? If not, what else was needed?
- Did the system seem to boost performance, whether subjectively or on a dyno?
- If the owner had it to do over again, would he buy the same system?

Headers
To get maximum performance out of a new exhaust system, a set of headers is essential. While it’s not mandatory, I recommend buying your headers and other exhaust components from the same manufacturer whenever possible. This usually ensures that everything fits properly and lines up correctly the first time.

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Fortunately, installing headers isn’t especially difficult on the C5; you’ll just need a little time and patience. Make sure the ones you buy don’t require any cutting, welding, fabrication, or other post-purchase modifications.

As you noted, you will need to choose either long- or short-tube headers for your C5. Long-tube headers improve scavenging and take advantage of exhaust pulses to emphasize power and torque throughout the rpm range. The downside is that, because they require the removal or relocation of the factory catalytic converters, they are not legal for use on street-driven vehicles.

Short-tube headers are compatible with the stock cats (and easier to install), but they tend to make less power. Consider the pros and cons of each type of header carefully before making your decision.

Part 1: Removing the Stock Exhaust Manifolds
While it is possible to install your headers and exhaust system using jackstands, the job is considerably easier if you have access to a lift. You’ll also need an assistant to provide an extra set of hands during the installation.

We’ll begin by clearing out some components to make sure we have a clear path to the factory exhaust manifolds.

1. Remove the battery shroud and battery.
2. Remove the two plastic coil covers.
3. Remove the serpentine belt and alternator.
4. Remove all of the spark plugs.
5. Unbolt and move the coil packs out of the way, taking care not mix the firing order. You can label the wires and coil packs to make this easier.
6. Loosen the primary O2 sensor from the collector of each exhaust manifold.
7. Unbolt the air-injection line from the top of each exhaust manifold.
8. Unbolt the bottom (collector) of the exhaust manifold at the three-bolt exhaust flange, where the manifold connects to the exhaust pipe. This needs to be done from the underside of the vehicle.
9. Unbolt the top of the exhaust manifold from the cylinder head and carefully remove the manifold through the top of the engine compartment.